Field of the Invention
Examples of the present disclosure generally relate to integrated circuits and, in particular, to capacitor structures in integrated circuits.
Description of the Related Art
Capacitors are used in integrated circuits (ICs) for a variety of purposes. Metal finger capacitors (“finger capacitors”) are example capacitor structures used in ICs. An LC tank or resonator is one type of circuit integrated in an IC that can utilize a finger capacitor. At low frequencies, such as frequencies less than 10 Gigahertz (GHz), the inductor (L) is normally the dominant factor for LC tank performance, since the quality factor (Q) of the inductor is typically 2-3 times lower than the Q of the finger capacitor (C). For higher frequencies, such as frequencies greater than 30 GHz, the Q of the finger capacitor drops dramatically, becoming less than the Q of the inductor. For such higher frequencies, the Q of the finger capacitor becomes the dominant limiting factor. As technology scaling continues, achieving a higher Q in finger capacitors without increasing surface area required in the IC remains a challenge.